We are investigating gene expression in nervous tissue, using as tools steroid hormones which regulate pituitary function and influence behavior by interacting directly with the nervous system. Our approach emphasizes the fate of the hormones themselves: entry into the brain, intracellular conversion to more or less active metabolites; binding to soluble intracellular "receptors" and transfer to the cell nucleus. We are also studying the consequences of steroid hormone binding on levels of brain enzymes and protein metabolism. Autoradiography and a variety of neurochemical and cell biological techniques are being employed. In addition to the brain-specific aspect of these hormone-brain interactions, we are also interested in their similarity to or difference from "receptors" in other "target" tissues. We are also studying developmental aspects of these interactions with two specific aims: 1) Studying the ontogeny of hormone "receptors" in brain compared with the development of functional neural systems these hormones are known to influence. 2) Investigating biochemically the mechanism of the "organizing" influences of androgen on the fetal or neonatal brain.